(7-x) - 50*(7-x)2+49=0

ОГЭ 2017 18 вариант

(7 - x) - 50*(7 - x)² + 49 = 050*(7 - x)² - (7 - x) - 49 = 0D = b²-4ac = 1 + 9800 = 9801 = 99²7 - x = 1+99/100 = 1          =>    x = 67 - x = 1-99/100 = -0,98    =>    x = 7,98Ответ: {6; 7,98}